BuddyPress.org

@jwack
– Yep

– Yes, it’s not the most accessible-friendly way to prevent splogging but we do require people use the code in order to register at all, instead of a captcha. And we haven’t had a single spammer since. But for the few who don’t know it, we also provide the link where they can easily find out what it is, especially if they feel too lazy to look it up (I would be, heh).

Since our targets are mostly local people or former residents, they tend to know what the zip code is. If you have a genre-specific site, perhaps a similar technique could be applied? Or maybe a developer here could help you to modify the code so it applies only to the blog registration? I’m more of a front-end user/designer so altering other dev’s code is way out of my league >_<;